The present invention relates to an axial loading cam arrangement for traction roller transmissions and to traction roller transmissions including such axial loading cams.
In traction roller transmissions the power transmitting traction members have to be held in engagement with one another with substantial forces which depend on the amount of torque to be transmitted. These transmissions therefore usually include loading cam structures which are subjected to the input or output torque applied to, or generated by, the transmission and which provide an axial engagement force for engagement of the traction members which corresponds to such torque.
A loading cam arrangement with load balls arranged between the camming surfaces is shown, for example, in U.S. Pat. No. 3,087,348 which relates to a toroidal transmission;
A loading cam arrangement with conical load rollers arranged between the camming surfaces is shown in U.S. Pat. No. 3,184,983 and a loading cam arrangement with cylindrical load rollers arranged between the camming surfaces is shown in U.S. Pat. No. 4,086,820. As pointed out earlier however the loading cam forces are extremely high and therefore require special and rugged cam structures capable of transmitting the high axial cam forces to the traction members for appropriate engagement. Because of deflections generated by the high cam forces it has not been possible to directly apply the high camming forces to the components which need to be engaged unless the particular components consisted of very thick-walled structures capable of transmitting the large forces without any bending. Such arrangements whether heavy-walled or double-walled to avoid transmission of flexing, however, are heavy and quite expensive.
It is therefore the principal object of the present invention to provide an axial loading cam structure and a transmission with such a loading cam structure which is relatively inexpensive and provides for better load distribution so that smaller components of lesser weight and with lower space requirements can be utilized for the transmission.